diff --git a/vars/functions.groovy b/vars/functions.groovy
index 5ff1a55..e9facb0 100644
--- a/vars/functions.groovy
+++ b/vars/functions.groovy
@@ -53,7 +53,7 @@ def deletePod (Map config) {
     }
 }
 
-def buildContainer (Map config, []String buildArg = []) {
+def buildContainer (Map config, List buildArg = []) {
     def ws = pwd()
     stage ("Build Container") {
         container ("kaniko") {